The specific focus of this group of studies is to elucidate further the mechanisms responsible for the altered brain circulation and metabolism in cerebral ischemia and to devise and test methods to modify the metabolic defect and improve tissue survival. Regional CBF measurements in various stages of experimental cerebral infarction will be correlated with known metabolic changes. The significance of previously observed changes in cerebral monoamines in ischemia will be investigated as will the role of cyclic nucleotides in brain ischemia. Studies on NH3 metabolism and uptake will be done to clarify the role of the increase in tissue NH3 during cerebral ischemia. Mechanisms of recovery from cerebral infarction will be studied utilizing the C142 deoxyglucose autoradiographic method.